The present disclosure is directed to the improved process of removing refractory metal core material, and more particularly use of production tooling for non-aqueous removal of refractory metal cores.
Cooled gas turbine airfoils are generally cast from nickel super alloys (e.g., IN100, Mar-M-200), or more advanced nickel alloys having improved creep strength at elevated temperature. Historically, cooled turbine airfoils utilize ceramic cores for creating the internal cooling configurations. More advanced cooling schemes utilize a combination of both ceramic cores and/or refractory metal cores. Ceramic core material is easily removed via autoclaving. Whereas refractory metal core removal up until now has required immersion within aggressive acids for significant lengths of time (e.g., hours/days). Such acids and duration can result in selective attack of the internal surfaces, sometimes resulting in cracking as a result of the retention of internal residual stresses from the casting process.
What is needed is an alternative, more environment/health and safety friendly process for removing molybdenum-alloy refractory metal cores without causing selective attack and/or cracking of the internal cooling passages.
In accordance with the present disclosure, there is provided a furnace for removing a molybdenum-alloy refractory metal core through sublimation comprising a retort furnace having an interior; a sublimation fixture insertable within the interior of the retort furnace, the sublimation fixture being configured to receive at least one turbine blade having the molybdenum-alloy refractory metal core; a flow passage is thermally coupled to the retort furnace and configured to heat a fluid flowing through the flow passage and deliver the fluid to the molybdenum-alloy refractory metal core causing sublimation of the molybdenum-alloy refractory metal core.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the flow passage being fluidly coupled to a coupling configured to receive air, and the flow passage being fluidly coupled to a junction at an end opposite the coupling, the junction being configured to fluidly couple to the sublimation fixture.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the flow passage is formed within a wall of the retort furnace.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the sublimation fixture comprises a blade receiver fluidly coupled to the flow passage, the blade receiver being configured to receive a root of the turbine blade.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the furnace for removing a molybdenum-alloy refractory metal core through sublimation further comprising a collector fluidly coupled to the interior of the retort furnace, wherein the collector is configured to collect waste discharged from the blade responsive to sublimation of the molybdenum-alloy refractory metal core.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the furnace for removing a molybdenum-alloy refractory metal core through sublimation further comprising an inner furnace box within an outer furnace box of the retort furnace, the inner furnace box configured to receive the sublimation fixture.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the inner furnace box comprises an enclosure coupled to a base at a joint having a seal between a wall of the enclosure and the base.
In accordance with the present disclosure, there is provided a furnace for removing a molybdenum-alloy refractory metal core from a blade through sublimation comprising a retort furnace comprising an outer furnace box having an interior; an inner furnace box within the interior, the inner furnace box comprising an enclosure coupled to a base; a sublimation fixture insertable within the inner furnace box, the sublimation fixture configured to receive at least one turbine blade having the molybdenum-alloy refractory metal core; a flow passage coupled to the sublimation fixture; the flow passage thermally coupled to the retort furnace configured to heat a fluid flowing through the flow passage and deliver the fluid to the molybdenum-alloy refractory metal core causing sublimation of the molybdenum-alloy refractory metal core; and a collector fluidly coupled to the interior of the outer furnace box, wherein the collector is configured to collect waste discharged from the blade responsive to sublimation of the molybdenum-alloy refractory metal core.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the flow passage is fluidly coupled to a coupling configured to receive air, and the flow passage is fluidly coupled to a junction at an end opposite the coupling, the junction being configured to fluidly couple to the sublimation fixture.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the flow passage is formed within a wall of the inner furnace box.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the sublimation fixture comprises a blade receiver fluidly coupled to the flow passage, the blade receiver configured to receive a root of the turbine blade.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the enclosure is coupled to the base at a joint having a seal between a wall of the enclosure and the base.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the sublimation fixture comprises a cavity formed between internal plenums opposite the blade receiver.
In accordance with the present disclosure, there is provided a process for removing a molybdenum-alloy refractory metal core from a turbine blade through sublimation comprising installing at least one turbine blade in a sublimation fixture; installing the sublimation fixture in a retort furnace; removing a molybdenum-alloy refractory metal core from the at least one turbine blade through sublimation with air; and capturing waste discharged from the blade responsive to sublimation of the molybdenum-alloy refractory metal core responsive to the sublimation.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising reusing the waste; and disposing of the waste.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising prior to the step of installing at least one turbine blade in a sublimation fixture casting the at least one blade with a ceramic core and the molybdenum-alloy refractory metal core; and removing the ceramic core.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising supplying air from an air source to a coupling fluidly coupled to the flow passage; heating the air flowing through the flow passage; supplying the air from the flow passage to a junction; and coupling the junction to the sublimation fixture.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising flowing the air through the sublimation fixture into the at least one turbine blade; and flowing the air through the turbine blade; contacting the molybdenum-alloy refractory metal core with the air.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the air is heated to a temperature of from 1300 degrees Fahrenheit to 2000 degrees Fahrenheit.
A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process step of installing the sublimation fixture in a retort furnace further comprising the retort furnace comprises an outer furnace box having an interior and an inner furnace box within the interior, the inner furnace box comprising an enclosure coupled to a base; and inserting the sublimation fixture within the inner furnace box.
Other details of the process and equipment are set forth in the following detailed description and the accompanying drawings wherein like reference numerals depict like elements.
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The inner furnace box 14 situated within the interior 18 includes a coupling 20 attached to an exterior 22 of a retort furnace wall 24. A flow passage 26 is coupled to the coupling 20. The coupling 20 can include a quick connect 44 configured to receive an external air supply line from an air source 45. The flow passage 26 fluidly connects with an interior 28 of the inner furnace box 14 (See
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The sublimation fixture 68 can include a thermocouple 88 seated in a thermocouple well 90. The thermocouples 88 can be placed strategically along the sublimation fixture 68 to provide for temperature data to operate the retort furnace 10.
The profile of the sublimation fixture 68 includes a cavity 92 formed opposite the blade receiver 80. The cavity 92 can be formed as a linear V with radius configuration that runs between the internal plenum legs 72. The cavity 92 serves a dual purpose. The first purpose of the cavity 92 is to reduce the overall weight of the sublimation fixture 68. The second purpose is to enlarge the surface area of the sublimation fixture 68 to improve the heat transfer from the inner furnace box 14 to the sublimation fixture 68. The air 46 flowing through the sublimation fixture 68 receives the thermal energy transferred from the inner furnace box 14 to the sublimation fixture 68. The sublimation fixture 68 having these features allows for shortened processing time for each set of turbine blades 74 mounted in the sublimation fixture 68 because the sublimation fixture 68 heats up faster, cools down faster, maintains more uniform temperature during the core removal operation process cycle, and maintains improved temperature uniformity during heating and cooling.
The collector 38 is configured to capture the waste 36 in the air 46 discharged from the sublimation of the molybdenum-alloy refractory metal cores 48. The hot air 46 flowing into and through the blades 74 passes over the molybdenum-alloy refractory metal cores 48 and sublimates the material. The air 46 discharges from the blade 74 into the interior 28 and flows to the collector 38. The waste 36 of molybdenum dioxide, and/or molybdenum trioxide in the waste 36 stream can be exhausted from the discharge 34 into the collector 38. The collector 38 can include a HEPA filtering system. The collector 38 can include a water entrainment tank configured to capture the molybdenum dioxide, and/or molybdenum trioxide. The molybdenum dioxide, and/or molybdenum trioxide can be reverted or disposed.
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There has been provided a process and tooling for non-aqueous removal of refractory metal cores. While the tooling for non-aqueous removal of refractory metal cores has been described in the context of specific embodiments thereof, other unforeseen alternatives, modifications, and variations may become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations which fall within the broad scope of the appended claims.
The instant application is a divisional of U.S. patent application Ser. No. 16/816,865 filed Mar. 12, 2020.
Number | Date | Country | |
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Parent | 16816865 | Mar 2020 | US |
Child | 17676430 | US |